Physiological Load and Breath-Holding in Artistic Swimming: A Scoping Review of the Impact of 2022-2025 Rule Changes

Background & Rationale： Artistic Swimming (formerly Synchronized Swimming) is undergoing its most significant transformation in history with the implementation of the World Aquatics 2022–2025 scoring system. This paradigm shift moves the sport from a focus on subjective artistic impression to a quantifiable "Degree of Difficulty" (DD). Under these new rules, athletes are compelled to increase the density of "Hybrid" elements and underwater breath-holding duration to accumulate higher scores, potentially pushing them to their physiological limits. Furthermore, the introduction of the "Base Mark" penalty creates a rigorous "all-or-nothing" judgment system, introducing significant psychological pressure that may exacerbate physiological stress and autonomic conflict. Objectives： This scoping review aims to systematically map the existing literature on physiological load and breath-holding characteristics in artistic swimming, with a specific focus on the implications of the 2022–2026 rule changes. The primary research questions include: 1.How do the new rules (quantified DD and increased Hybrids) affect acute physiological load (e.g., heart rate, blood lactate, VO2) and apnea characteristics in elite athletes? 2.Do current routines induce higher anaerobic metabolism and more severe hypoxemia compared to the pre-2022 era? 3.Does the psychological pressure of "Base Mark" penalties influence physiological responses, such as heart rate variability (HRV)? 4.What are the safety implications for different age groups, particularly following the removal of breath-holding limits for junior athletes? Methodology： This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. Eligibility criteria were established using the Population–Concept–Context (PCC) framework, including competitive artistic swimmers of all levels and excluding recreational participants. The review synthesizes evidence from peer-reviewed original research investigating physiological load (cardiovascular, metabolic, oxygenation) and breath-holding responses in training, competition, or simulated settings. Expected Outcomes： The project will provide a comprehensive synthesis of physiological demands in the new rule era. The findings are expected to: 1.Identify knowledge gaps regarding the physiological safety of high-DD routines. 2.Provide evidence-based recommendations for World Aquatics regarding safety rules (e.g., potential re-introduction of breath-holding limits). 3.Assist coaches in optimizing periodization and training strategies to manage the increased anaerobic and hypoxic demands.